Mahaffey: I’ll start with the big one: Are we alone in the universe?
Shostak: It’s possible. We haven’t found any life, let alone intelligent life, beyond Earth. I mean, we haven’t found any yet. There are many, many planets. If it turns out that Earth is the only one with beings that run around and think about stuff, that would make us some sort of miracle, and I can’t bring myself to believe that. If the explanation for your scientific hypothesis is “It’s a miracle,” you’re not going to get published, and you shouldn’t.
You might look at a million solar systems and fail to find a signal, but that doesn’t prove they’re all sterile.
Mahaffey: So the scale of the universe makes it difficult to produce a definitive answer.
Shostak: Yes. One hundred years ago astronomers figured that the sun and the various planets orbiting it were close to the center of this one and only galaxy. But all that changed in the mid-1920s, when people like Edwin Hubble figured out that the little smudges on photos of the night sky are not objects in our galaxy at all; they’re other galaxies. It turned out that ours was just one of many. As of today we can see at least 200 billion galaxies. There are many more we can’t see because they are so far away that the light from them hasn’t yet reached us. In the Milky Way, our galaxy, there are 200 to 300 billion solar systems. And one out of every two or three has a planet the right distance from its star to have the kind of temperatures that you enjoy in North Carolina.
“Last year, I had a life-changing experience at 90 years old. I went to space, after decades of playing an iconic science-fiction character who was exploring the universe. I thought I would experience a deep connection with the immensity around us, a deep call for endless exploration.
"I was absolutely wrong. The strongest feeling, that dominated everything else by far, was the deepest grief that I had ever experienced.
"I understood, in the clearest possible way, that we were living on a tiny oasis of life, surrounded by an immensity of death. I didn’t see infinite possibilities of worlds to explore, of adventures to have, or living creatures to connect with. I saw the deepest darkness I could have ever imagined, contrasting so starkly with the welcoming warmth of our nurturing home planet.
"This was an immensely powerful awakening for me. It filled me with sadness. I realized that we had spent decades, if not centuries, being obsessed with looking away, with looking outside. I did my share in popularizing the idea that space was the final frontier. But I had to get to space to understand that Earth is and will stay our only home. And that we have been ravaging it, relentlessly, making it uninhabitable" (emphasis added).